Muffler



April 29, 1930.

S. $TRANAHAN- MUFFLER Filed Jam.v 2'4, 192V Patented Apr. 29, 1.930

UNITED STATES SAMUEL A. STRANAWHAN, OF FLINT, MICHIGAN, ASSIGNOR TO GENERAL MOTORS COR- PATENT OFFICE 'l roRATIoN, or' DETROIT, MICHIGAN, A CORPORATION or DELAWARE MUFFLER Application led January 24, 1927. Serial No. 163,155.

My invention relates to an improved mufller of the type commonlyv used in the exhaust pipe of internal combustion engines and has for its principal object the provision of a muffler which is so designed that the maximum silencing eiect will be obtained with very little back pressure.

Another Objectis to so construct a muffler that it will not only reduce the sound of the explosion but at the same time will be free from vthe ringing, metallic, sound so often present in the usual muillers.

Other objects and advantages Will be ap'- parent upon referring to the specification and accompanying drawing, in which:

Fig. 1 is a longitudinal sectional view through the center of my improved muiler.

Fig. 2 is a section taken on line 2 2 of Fi 1; i l

ig. 3 is a section taken on line 3-3 of Fig. 1.

The numeral 10 indicates a casing having end plates 12 and 14 preferably welded in place to provide an air tight compartment. The front plate 12 is formed with a flange 16 to receive the exhaust pipe leading from the engine. The rear plate 14 also has a flange 18 to which is attached a pipe leading to the rear of the vehicle where the exhaust gases are discharged into the atmosphere. In addition this plate is constructed With a conical shaped portion 20 for a purpose to be described later. Within the casing' there are live concave-convex discs held in place by being spot Welded to the casing. These discs have different numbers of perforations in them to permit thel proper expansion of the exhaust gases. For example in the particular embodiment illustrated, disc 22 has ninety small perforations and disc 24 has eighty-two perforations of the same diameter. Disc 26 has one large opening and the next disc 28 has seventy perforations of substantially the same size as vthose in discs 22 and 24. The last disc 30 has an opening of substantially the same diameter as that-in disc 26 and is provided with a tapered tube 32 the large end ofi'which is preferably spot Welded 'to the disc concentric with the opening in the latter, the small end being spaced a short distance away from the rear plate 14 ata point tube 32 and out t rough the opening 46 to i the atmosphere.

Due to the fact that there is a constant high velocity flow of gases throughl the tapered tube 32, it is obvious that there Will be a partial vacuum in chamber 48 because of the Venturi eiiect caused by the arrangement of tube 32 within the conical shaped portion 20 of plate 14. The purpose of this vacuum chamber is to eliminate the ringing or metallic noise usuallyl present in pressed steel mulers. It also servesto. give the sound of the escaping gases a very loW pitch which is scarcely audible.

It isthought from the foregoing taken in connectionwith the accompanying drawing that .the construction and operation of the device Will be apparent to those skilled in the art, andthat various changes in size, shape, and proportion and details of construction lmay be made Without departing from the spirit and scope of the vappended claims.

I claim: Y

1. A muiiler rcomprising a casing, means in said casing for breaking up the stream of exhaust gases into a plurality of smaller streams, means for concentrating them into a single stream, a tube for discharging said single stream, and a vacuum chamber surrounding said tube for the purpose of reducing thesound of the discharge. l

2. A muier comprising a casing, spaced means in the casing for dividing the stream of exhaust gases into several smaller streams,

the space between said means serving as an expansion chamber, means for concentrating the smaller streams into a single stream, a tube carried by said second means from which said single stream is discharged, and a vacuum chamber surrounding said tube for the '5 purpose of reducing, the sound of the discharge.

3. A 'muler comprising a casing, a series of discs containing dilerent numbers of perforations held in the casing, and a tube I carried by one of said discs through which the exhaust gases are discharged, and a vac-` uum chamber surrounding said tube for the purpose of reducing the sound of the discharge.

4. A muier comprising a cylindrical casing having end plates, one of said end Plates being formed with a conical shaped portion,

4perforated discs secured in the casing, and a tube carried by one of said discs, the rear end 20 of the vtube .lying within the conical shaped I rtion, thespaces between the various discs orming expansion chambers and the space between one of said end plates and the adja- Vcent disc forming a vacuum chamber.

5. A muler comprising a cylindrical casing, front and rearend plates held in the casin ,central openings in the end plates, a lu- -ra ity of discs containing different num ers ofsmall perforations, an intermediate disc having a relatively larger opening, an end disc having a large central opening, and a tube secured to the end disc concentric with the opening therein, the opposite end of the tube lying within the-opening in the rear en d plate, the space between ythe end disc and the' ear end plate constituting a vacuum chamer. i 6. A muilier comprising a casing having an inlet and an outlet, a cross-wall for said cas- '40 ing having a plurality of relatively small aperturestherethrough, a second cross-wall in said casing between the lirst cross-wall and the outlet and being imperforate except for a single relatively large aperture and a tubul lar conduit surrounding said relatively large aperture and projecting toward said outlet and cooperating with said second cross-wall to provide a dead space surrounding the conduit, the parts beingA constructed and ar' 50 ranged to reduce ressure in the space surrounding said con uit. v v In testimony whereof I aiiix m signature.

SAMUEL' A. STRA AHAN. 

